MC7457RX1267LC Datasheet, PDF (17/71 Pages) Freescale Semiconductor, Inc – Microprocessor

Electrical and Thermal Characteristics
5.2 AC Electrical Characteristics
This section provides the AC electrical characteristics for the MPC7457. After fabrication, functional parts
are sorted by maximum processor core frequency as shown in Section 1.5.2.1, “Clock AC Specifications,”
and tested for conformance to the AC specifications for that frequency. The processor core frequency is
determined by the bus (SYSCLK) frequency and the settings of the PLL_CFG[0:4] signals. Parts are sold
by maximum processor core frequency; see Section 1.11, “Ordering Information.”
5.2.1 Clock AC Specifications
Table 8 provides the clock AC timing specifications as defined in Figure 6 and represents the tested
operating frequencies of the devices. The maximum system bus frequency, f_SYSCLK, given in Table 8 is
considered a practical maximum in a typical single-processor system. The actual maximum SYSCLK
frequency for any application of the MPC7457 will be a function of the AC timings of the MPC7457, the
AC timings for the system controller, bus loading, printed-circuit board topology, trace lengths, and so
forth, and may be less than the value given in Table 8. For information regarding the use of spread
spectrum clock generators, see Section 9.1.3, “System Bus Clock (SYSCLK) and Spread Spectrum
Sources.” PLL configuration and bus-to-core multiplier information is found in Section 9.1.1, “Core
Clocks and PLL Configuration.”
Table 8. Clock AC Timing Specifications
At recommended operating conditions. See Table 4.
Maximum Processor Core Frequency
Characteristic
Symbol 867 MHz
1000 MHz
1200 MHz
1267 MHz Unit Notes
Min Max Min Max Min Max Min Max
Processor frequency
f_core
600 867 600 1000 600 1200 600 1267 MHz
1
VCO frequency
f_VCO 1200 1733 1200 2000 1200 2400 1200 2534 MHz
1
SYSCLK frequency
f_SYSCLK 33 167 33 167 33 167 33 167 MHz 1, 2
SYSCLK cycle time
t_SYSCLK 6.0
30
6.0
30
6.0
30
6.0
30
ns
2
SYSCLK rise and fall time
t_KR, t_KF —
1.0
—
1.0
—
1.0
—
1.0
ns
3
SYSCLK duty cycle measured t_KHKL/
40
60
40
60
40
60
40
60
%
4
at OV_DD/2
t_SYSCLK
SYSCLK cycle-to-cycle jitter
— 150 — 150 — 150 — 150 ps
5, 6
MPC7457 RISC Microprocessor Hardware Specifications, Rev. 8
Freescale Semiconductor
17